\begin{tikzpicture}[>=Stealth]
    \draw (0,0) rectangle (3,4);
    \filldraw[pattern=horizontal lines light gray] (0,0) rectangle (3,2);

    \draw (0,0) -- (0,-0.5) (3,0) -- (3,-0.5) [<->] (0,-0.35) -- (3,-0.35);
    \node [fill=white] at (1.5,-0.35) {$d$};
    
    \draw (0,0) -- (-0.5,0) (0,4) -- (-0.5,4) [<->] (-0.35,0) -- (-0.35,4);
    \node [fill=white] at (-0.35,2.5) {$h$};

    \draw (3,0) -- (3.5,0) (3,2) -- (3.5,2) [<->] (3.35,0) -- (3.35,2);
    \node [fill=white] at (3.35,1) {$x$};

    \draw (1.5,4.5) [rounded corners=.3cm] -- (1.5,5.5)-- (2.5,5.5);
    \draw (1.8,4.5) [rounded corners=.25cm] -- (1.8,5.2)-- (2.5,5.2);
    \draw[pattern=dots,pattern color=gray,dotted] (1.5,4.5) -- (1.8,4.5) -- (2.0,2) -- (1.2,2) -- cycle;
\end{tikzpicture}
